1. Field of the Invention
The present invention relates to a locating and clamping apparatus for use, for example, in an automotive body assembling process to position a panel-shaped workpiece with a locating pin and to clamp the positioned workpiece.
2. Description of the Related Art
FIGS. 14A and 14B of the accompanying drawings show a conventional locating and clamping apparatus based on the disclosure of Japanese Patent Application Unexamined Publication (KOKAI) No. 2002-337770 (patent document 1). In the locating and clamping apparatus according to the patent document 1, a clamp body 10 is provided with a locating pin 11 projecting therefrom. A seating surface 12 is formed outside a lower portion of the locating pin 11. A clamp arm is movably disposed in both a longitudinal hole 13 of the clamp body 10 and a hollow hole of the locating pin 11. An output member of a direct acting actuator 17 is reciprocatably disposed in the longitudinal hole 13 of the clamp body 10. The clamp arm and the output member are connected to each other through a connecting pin. A fulcrum pin 19 extends through a guide slot 18 formed in the clamp arm. The fulcrum pin 19 is supported by fulcrum pin supporting holes in the clamp body 10. FIG. 14A shows a state where the locating pin 11 has been inserted through a positioning hole (locating hole) in a panel-shaped workpiece 24, and the workpiece 24 has been clamped between a distal end portion 23 of the clamp arm and the seating surface 12.
If a welding operation is performed on the workpiece 24 clamped as stated above, spatter (slags and metal particles) scattered during welding enters the longitudinal hole 13 of the clamp body 10 through an opening 22 that allows the hollow hole of the locating pin 11 to communicate with the outside. To remove spatter having entered the clamp body 10, the locating and clamping apparatus according to the patent document 1 needs to be disassembled and cleaned periodically. Conventionally, however, a spatter discharge hole 25 is formed in the clamp body 10 to provide communication between the longitudinal hole 13 and the outside, thereby allowing spatter to be discharged from the spatter discharge hole 25 without the need to disassemble the apparatus. Therefore, the spatter discharge hole 25 is shown in FIG. 14A. It is also conventional practice to arrange the locating and clamping apparatus so as to prevent the fulcrum pin 19 from coming off, as shown in FIG. 14B, although this arrangement is not explicitly stated in the patent document 1. That is, end portions of the fulcrum pin 19 are made to project to the outside from the fulcrum pin supporting holes. Split pins 27 are passed through respective through-holes pierced in both end portions of the fulcrum pin 19, and the distal ends of the split pins 27 are bent as shown in the figure.
In the prior art shown in FIGS. 14A and 14B, spatter may enter the longitudinal hole 13 of the clamp body 10 through the spatter discharge hole 25 and accumulate therein, depending on the use conditions of the locating and clamping apparatus. Consequently, the frequency with which welding or other operation is suspended to perform a spatter discharge operation increases, resulting in a reduction in the operating efficiency. Further, to remove the fulcrum pin 19 to disassemble the locating and clamping apparatus, it is necessary to pull out the split pins 27 by straightening the bent end portions of the split pins 27 with a specially prepared tool. Therefore, the operating efficiency is unfavorably low.